Radiation protection in diagnostic and interventional radiology
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IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology. RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY. L16.2: Optimization of Protection in Fluoroscopy. Introduction. Subject matter : radiation protection in fluoroscopy equipment

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Radiation protection in diagnostic and interventional radiology

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

RADIATION PROTECTION INDIAGNOSTIC ANDINTERVENTIONAL RADIOLOGY

L16.2: Optimization of Protection in Fluoroscopy


Introduction

Introduction

  • Subject matter : radiation protection in fluoroscopy equipment

  • Both physical and technical parameters may have an influence on patient and staff dose.

  • Good radiation protection policy and personnel skill are essential for reducing both staff and patient exposures.

16.2: Optimization of protection in fluoroscopy


Content

Content

  • Factors affecting staff doses

  • Factors affecting patient doses

  • Examples of doses

  • Protection tools

  • Radiation protection rules

16.2: Optimization of protection in fluoroscopy


Overview

Overview

  • To become familiar with the application of practical radiation protection principles to fluoroscopy system.

16.2: Optimization of protection in fluoroscopy


Part 16 2 optimization of protection in fluoroscopy

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

Part 16.2: Optimization of Protection in Fluoroscopy

Topic 1: Factors affecting staff doses


Refresher slide absorption and scatter

Refresher slide: absorption and scatter

X-Ray tube

For every 1000 photons reaching the patient, about 100-200 are scattered, about 20 reach the image detector, and the rest are absorbed (= radiation dose)

Scatter x rays also obeys the Inverse Square Law, so distance from the patient improves safety

In radiology, scatter mainly directed towards the source

16.2: Optimization of protection in fluoroscopy


Factors affecting staff doses i

Factors affecting staff doses (I)

  • The main source of radiation for the staff in a fluoroscopy room is the patient (scattered radiation).

  • The scattered radiation is not uniform around the patient.

  • The dose rate around the patient is a complex function of a great number of factors.

16.2: Optimization of protection in fluoroscopy


Factor affecting staff doses ii

Factor affecting staff doses (II)

HEIGHT OF STAFF

FACTORS

AFFECTING

RELATIVE POSITION WITH

STAFF DOSE

RESPECT TO THE PATIENT

IRRADIATED PATIENT VOLUME

X RAY TUBE POSITION

kV, mA and time (NUMBER AND

CHARACTERISTICS OF PULSES)

EFFECTIVE USE OF ARTICULATED

SHIELDING AND/OR PROTECTION

GOGGLES

16.2: Optimization of protection in fluoroscopy


Factor affecting staff doses iii

Factor affecting staff doses (III)

ANGLE DEPENDENCE

Scattered dose rate is higher near the area where the X-ray beam enters the patient

100 kV

0.9 mGy/h

1 mA

0.6 mGy/h

11x11 cm

0.3 mGy/h

1m patient distance

patient thickness 18 cm

16.2: Optimization of protection in fluoroscopy


Factor affecting staff doses iv

Factor affecting staff doses (IV)

FIELD SIZE DEPENDENCE

Scattered dose rate is higher when field size increases

11x11 cm

17x17 cm

17x17 cm

100 kV

0.8 mGy/h

1.3 mGy/h

1 mA

0.6 mGy/h

1.1 mGy/h

0.3 mGy/h

0.7 mGy/h

1m patient distance

Patient

thickness 18 cm

16.2: Optimization of protection in fluoroscopy


Factor affecting staff doses v

Factor affecting staff doses (V)

DISTANCE VARIATION

mGy/h at 0.5m

mGy/h at 1m

Scattered dose rate is lower when distance to the patient increases

100 kV

1 mA

11x11 cm

16.2: Optimization of protection in fluoroscopy


Factor affecting staff doses vi

INTENSIFIER UP

THE BEST

CONFIGURATION

X-RAY TUBE DOWN

SAVES A FACTOR OF

3 OR MORE IN DOSE

X-RAY TUBE UP

IN COMPARISON

TO:

INTENSIFIER DOWN

Factor affecting staff doses (VI)

Tube undercouch position reduces, in general, high dose rates to the specialist’s eye lens

16.2: Optimization of protection in fluoroscopy


Factor affecting staff doses vii

Factor affecting staff doses (VII)

Tube undercouch position reduces, in general, high dose rates to the specialist’s eye lens

X-Ray tube

mGy/h

100 kV

2.2 (100%)

1 m

2.0 (91%)

20x20 cm

1.3 (59%)

mGy/h

1 Gy/h

(17mGy/min)

1.2 (55%)

1.2 (55%)

1.2 (55%)

1 Gy/h

1m patient distance

(17 mGy/min)

1.3 (59%)

20x20 cm

2.2 (100%)

100 kV

1 m

1m patient distance

X-Ray tube

16.2: Optimization of protection in fluoroscopy


Staff and patient dose are partially linked

Staff and patient dose are partially linked

16.2: Optimization of protection in fluoroscopy


Staff and patient dose are partially linked1

Staff and patient dose are partially linked

16.2: Optimization of protection in fluoroscopy


Factors affecting staff and patient doses i

Factors affecting staff and patient doses (I)

PATIENT SKIN DOSE AND THE LEVEL OF SCATTERED RADIATION INCREASE SUBSTANTIALLY

IF PATIENT SIZE INCREASES

16.2: Optimization of protection in fluoroscopy


Factors affecting staff and patient doses ii

Factors affecting staff and patient doses (II)

CHANGING FROM NORMAL FLUOROSCOPY MODE TO THE HIGH DOSE RATE MODE

INCREASES DOSE RATE BY A FACTOR OF 2 OR MORE

16.2: Optimization of protection in fluoroscopy


Factors affecting staff and patient doses iii

Factors affecting staff and patient doses (III)

INCREASES PATIENT ENTRANCE DOSE BY A FACTOR OF 2 TO 6

THE USE OF THE ANTISCATTER GRID

16.2: Optimization of protection in fluoroscopy


Part 16 2 optimization of protection in fluoroscopy1

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

Part 16.2: Optimization of Protection in Fluoroscopy

Topic 2: Factors affecting patient doses


Factors affecting patient doses i

Factors affecting patient doses (I)

CHANGING FROM HIGH TO LOW NOISE MODE (FOR CINE AND DSA - Digital Subtraction Angiography)

INCREASES DOSE PER IMAGE BY A FACTOR OF 2 TO 10

16.2: Optimization of protection in fluoroscopy


Factors affecting patient doses ii

Factors affecting patient doses (II)

CHANGING FROM CONVENTIONAL FLUOROSCOPY TO DIGITAL MODE

CAN DECREASE DOSE RATE DOWN TO 25%

16.2: Optimization of protection in fluoroscopy


Factors affecting patient doses iii

Factors affecting patient doses (III)

INTENSIFIER

DIAMETER

RELATIVE PATIENT

ENTRANCE DOSE

12" (32 cm) dose 100

9" (22 cm) dose 150

6" (16 cm) dose 200

4.5" (11 cm) dose 300

16.2: Optimization of protection in fluoroscopy


Factors affecting patient doses iv

Factors affecting patient doses (IV)

CAN INCREASE PATIENT ENTRANCE DOSE OF A FACTOR UP TO 3

CHANGING TO A SMALLER IMAGE INTENSIFIER FIELD

16.2: Optimization of protection in fluoroscopy


Part 16 2 optimization of protection in fluoroscopy2

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

Part 16.2: Optimization of Protection in Fluoroscopy

Topic 3: Examples of doses


Example of dose per frame ge cgr advantix lcv

Example of dose per frame GE-CGR Advantix LCV

TYPICAL

DOSE

4 mGy/im. or

0.1 mGy/fr

B mode:

C mode:

D mode:

A mode:

DOSE

DOSE

DOSE

DOSE 1

FACTOR 2.5

FACTOR 5

FACTOR 10

high noise

low noise

16.2: Optimization of protection in fluoroscopy


Example of entrance dose rate in fluoroscopy

Example of entrance dose rate in fluoroscopy

GE-CGR Advantix LCV (Fluoroscopy)

LOW DOSE 10 mGy/min

MEDIUM DOSE 20 mGy/min

HIGH DOSE 40 mGy/min

16.2: Optimization of protection in fluoroscopy


Example of scattered dose rate

Example of scattered dose rate

Scattered dose is higher at the X-ray tube side

16.2: Optimization of protection in fluoroscopy


Example of dose rate around mobile c arm

Image Intensifier

1.2

Patient

3

6

12

X-ray tube

100 cm 50 cm 0

Scale

Example of dose rate around mobile C-arm

All Contour values in µGy/min

16.2: Optimization of protection in fluoroscopy


Part 16 2 optimization of protection in fluoroscopy3

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

Part 16.2: Optimization of Protection in Fluoroscopy

Topic 4: Protection tools


Protection tools i

Protection tools (I)

THYROID SHIELD

SCREEN AND GOGGLES

CURTAIN

16.2: Optimization of protection in fluoroscopy


Protection tools ii

Protection tools (II)

100 kV

TRANSMITTED INTENSITY

DIRECT BEAM

90 %

80 %

SCATTERED

RADIATION

LEADED

FOR THE SAME

GLOVE

TACTILE PERCEPTION

100 kV

DIRECT BEAM

70 %

60 %

SCATTERED

WITH W THE

RADIATION

GLOVE

ATENUATION IS  3 TIMES

WITH W

BETTER THAN WITH Pb!!

16.2: Optimization of protection in fluoroscopy


Personal dosimetry

Personal dosimetry

Several personal dosemeters are recommended

From:Avoidance of radiation injuries from interventional procedures. ICRP draft 2000

16.2: Optimization of protection in fluoroscopy


Part 16 2 optimization of protection in fluoroscopy4

IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

Part 16.2: Optimization of Protection in Fluoroscopy

Topic 5: Radiation protection rules


Practical radiation protection rules i

Practical radiation protection rules (I)

ARTICULATED SHIELDING, LEADED APRONS, GLOVES, THYROID PROTECTORS, ETC, MUST BE READILY AVAILABLE IN THE X-RAY ROOMS

POSSIBLE

PROBLEM:

THEY MUST BE USED PROPERLY

16.2: Optimization of protection in fluoroscopy


Practical radiation protection rules ii

Practical radiation protection rules (II)

REGULAR QUALITY CONTROL

CHECKS MUST BE

ESTABLISHED

POSSIBLE

PROBLEM:

STAFF MUST SCHEDULE THESE

CHECKS AND PROVIDE

SUFFICIENT ROOM AVAILABILITY

16.2: Optimization of protection in fluoroscopy


Practical radiation protection rules iii

Practical radiation protection rules (III)

DOSE RATES MUST BE KNOWN IN EACH OPERATIONAL MODE AND FOR EACH INTENSIFIER INPUT SCREEN SIZE

CRITERIA FOR THE CORRECT USE OF ANY GIVEN OPERATION MODE MUST BE ESTABLISHED

16.2: Optimization of protection in fluoroscopy


Practical radiation protection rules iv

Practical radiation protection rules (IV)

  • IMPORTANT PARAMETERS:

  • SOURCE-TO- SKIN DISTANCE

  • PATIENT-IMAGE INTENSIFIER DISTANCE

  • PATIENT DOSE WILL INCREASE IF :

  • THE SOURCE-TO-SKIN DISTANCE IS SHORT

  • THE PATIENT-IMAGE INTENSIFIER DISTANCE IS LARGE

16.2: Optimization of protection in fluoroscopy


Equipment and specialist i

Equipment and specialist (I)

SPECIALIST

DEPENDENT

EQUIPMENT

DEPENDENT

SETTINGS MADE BY

THE TECHNICAL

SERVICE

NUMBER OF IMAGES

DOSE AND IMAGE AT

THE INTENSIFIER

RECORDED FOR EACH

INPUT

PROCEDURE

16.2: Optimization of protection in fluoroscopy


Equipment and specialist ii

Equipment and specialist (II)

EQUIPMENT CHARACTERISTICS

THE ROLE OF THE SPECIALIST

TO KNOW THE ACTUAL INTENSIFIER PERFORMANCE AND THE REQUIRED DOSE RATE

ACTUAL INTENSIFIER PERFORMANCE CAN REQUIRE INCREASE IN DOSE RATE

16.2: Optimization of protection in fluoroscopy


Equipment and specialist iii

Equipment and specialist (III)

EQUIPMENT CHARACTERISTICS

THE ROLE OF THE SPECIALIST

GOOD WORKING CONDITIONS OF THE AUTOMATIC BRIGHTNES CONTROL AND THE POSSIBILITY TO DISABLE IT

USE IT PROPERLY IN ORDER TO AVOID HIGH DOSE RATE WHEN LEADED GLOVES ARE IN THE BEAM

16.2: Optimization of protection in fluoroscopy


Equipment and specialist iv

Equipment and specialist (IV)

EQUIPMENT CHARACTERISTICS

THE ROLE OF THE SPECIALIST

EFFECTIVE USE OF THE COLLIMATION

EASY SELECTION OF FIELD COLLIMATION

16.2: Optimization of protection in fluoroscopy


Equipment and specialist v

Equipment and specialist (V)

EQUIPMENT CHARACTERISTICS

THE ROLE OF THE SPECIALIST

  • GRID FACTOR

  • INTENSIFIER PERFORMANCE

  • LEVEL OF NOISE, PULSE RATE, PULSE LENGTH, ETC.

PROTOCOL 

TOTAL PATIENT DOSE PER PROCEDURE

16.2: Optimization of protection in fluoroscopy


Radiation risk for staff

Radiation risk for staff

EQUIPMENT CHARACTERISTICS

THE ROLE OF THE SPECIALIST

DISTANCE AND RELATIVE POSITION OF THE STAFF WITH RESPECT TO THE PATIENT

ROOM DIMENSIONS

SHIELDING THICKNESS

X-RAY SYSTEM POSITION

16.2: Optimization of protection in fluoroscopy


Summary i

Summary (I)

  • Many physical factors may significantly affect patient and staff dose while working with a fluoroscopy equipment: beam geometry, distance from the source, Image Intensifier diameter, and type of fluoroscopy system.

  • There exist practical RP rules which allow to reduce such exposures

16.2: Optimization of protection in fluoroscopy


Summary ii golden rules

Summary (II): ”Golden rules”

  • Keep the II close to the patient

  • Do not overuse magnification modes

  • Keep the x-ray tube at maximal distance from patient

  • Use higher kVp where possible

  • Wear protective aprons and radiation monitors, and know where scatter is highest

  • Keep your distance, as far as is practicable

16.2: Optimization of protection in fluoroscopy


Where to get more information

Where to Get More Information

  • Wagner LK and Archer BR. Minimising risks from fluoroscopic x rays. Third Edition. Partners in Radiation Management (R.M. Partnership). The Woodlands, TX 77381. USA 2000.

  • Avoidance of radiation injuries from medical interventional procedures. ICRP Publication 85.Ann ICRP 2000;30 (2). Pergamon

  • Radiation Dose Management for Fluoroscopically-Guided Interventional Medical Procedures, NCRP Report No. 168, National Council on Radiation Protection and Measurement. Bethesda, MD. 2010

  • Interventional Fluoroscopy: Physics, Technology, Safety, S. Balter, Wiley-Liss, 2001

16.2: Optimization of protection in fluoroscopy


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